PolarConverter
PolarConverter is a free, open-source Java command-line tool for converting Minecraft Java Edition worlds from Anvil format to Polar format for Minestom-base…
What PolarConverter is
PolarConverter is a free, open-source Java command-line tool for converting Minecraft Java Edition worlds from Anvil format to Polar format for Minestom-based servers. It can process a complete world or limit conversion to chunks within an optional radius around coordinates (0,0). The source folder must contain a region folder and level.dat file, and Java 25 or later is required. Before conversion, the tool checks whether the world’s DataVersion matches the version supported by Minestom; a mismatch stops the process with an error. PolarConverter starts a minimal offline Minestom server to provide block registries and NBT support, reads Anvil chunks, converts blocks and metadata, and writes a .polar file. Listed dependencies are Minestom, a Minecraft server library, and Polar for world-format support. The project uses the MIT License and is available on GitHub. Its releases page states that there are no releases.
Good
- Converts complete worlds or selected chunk radii
- Writes Polar-format .polar files
- Checks DataVersion compatibility before conversion
- Open-source under the MIT License
- Supports Java Edition Anvil input
Watch out
- Requires Java 25 or later
- DataVersion mismatch stops conversion
- GitHub lists no releases
Who it suits
It is for people preparing Minecraft Java Edition Anvil worlds for Minestom-based servers, especially those needing full or radius-limited conversion.
Verdict
PolarConverter focuses narrowly on moving Anvil worlds into Polar format for Minestom. Its radius option and compatibility check are useful, but Java 25 and matching DataVersion are required.
The facts
Each one read from PolarConverter's own pages, with the date it was checked.
What it does
- Conversion process
- It starts a minimal offline Minestom server for block registries and NBT support, reads Anvil chunks, converts blocks and metadata, and writes a .polar file.checked 4 Oct 2026
- Conversion scope
- It supports full world conversion or conversion within a specified chunk radius around (0,0).checked 7 Oct 2026
- Dependencies
- The project lists Minestom and Polar as dependencies for server library and world format support.checked 7 Oct 2026
- Downloads
- The GitHub releases page states that there are no releases.checked 7 Oct 2026
- Full-world conversion
- The converter can process an entire world.checked 4 Oct 2026
- Input files
- The input world folder must contain a region folder and level.dat file.checked 7 Oct 2026
- Input requirements
- The project requires Java 25+ and a Java Edition Anvil world containing a region folder and level.dat file.checked 4 Oct 2026
- Intended users
- The project describes compatibility with Minestom based servers, making it relevant to users converting Minecraft worlds for those servers.checked 7 Oct 2026
- License
- The project states that it is licensed under the MIT License.checked 7 Oct 2026
- Notable limit
- Conversion stops with an error when the world's DataVersion does not match the version supported by Minestom.checked 7 Oct 2026
- Operation
- The tool starts a minimal offline Minestom server to provide block registries and NBT support during conversion.checked 7 Oct 2026
- Output
- The converter writes the result as a .polar file.checked 7 Oct 2026
- Partial conversion
- An optional radius limits conversion to chunks within that radius of coordinates (0,0).checked 4 Oct 2026
- Purpose
- PolarConverter converts Minecraft Java Edition worlds in Anvil format into Polar world format for Minestom based servers.checked 7 Oct 2026
- Requirements
- The README lists Java 25 or later and a Minecraft Java Edition world in Anvil format as requirements.checked 7 Oct 2026
- Version check
- Before converting, it checks that the world's DataVersion matches the Minestom server's supported version.checked 7 Oct 2026
- Version requirement
- The world’s DataVersion must match the Minestom server’s supported version; otherwise conversion stops with an error.checked 4 Oct 2026
The company
- Maker profile
- The GitHub profile describes its developer as focused on creating software, usually for Minecraft.checked 4 Oct 2026
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